glGenTextures
returns n texture names in textures. There is no guarantee that the names
form a contiguous set of integers; however, it is guaranteed that none
of the returned names was in use immediately before the call to glGenTextures.

The generated textures have no dimensionality; they assume the dimensionality
of the texture target to which they are first bound (see glBindTexture).

Texture names returned by a call to glGenTextures are not returned by subsequent
calls, unless they are first deleted with glDeleteTextures.